It has recently become extremely popular for restaurants, fast-food establishments, and even supermarkets to Provide salad bars wherein patrons can prepare their own salads from freshly cut vegetables and fruits. However, these various salad ingredients will show physical signs of deterioration, such as wilting, drying, shrinking or browning, within a fairly short time period. After such physical deterioration, these fruits and vegetables are no longer marketable. In addition, certain fast-food restaurants now offer ready-made salads which are prepared and refrigerated, but these too must be discarded if not purchased after a certain period of time. Although the problem of preservation of fresh fruits and vegetables has been with us since these products were first marketed, the problem is a particularly marked one at present due to the great prevalence of freshly cut produce in salad bars and prepared, containered salads which have extremely short shelf lives.
Many attempts have been made over the years to combat the problems of browning, wilting, etc. in cut or whole fruit and vegetable matter. Various methods and compositions have been invented for combatting oxidative deterioration in these products, such as described in U.S. Pat. Nos. 4,140,649; 3,987,208; 3,814,820; and 3,533,510. In these patents, active agents disclosed for use in preventing deterioration include ascorbic acid, other edible acids, and other sulfites, sodium phosphates, sodium ascorbate, and potassium sorbate. Dry treatment with CMC and optional gums including locust bean, guar, carragaum, tragacanth, alginates, acacia, bentonite and agar have been used with fruit acids as a dry treatment for fruits to preserve them during heat treatment. It is highly desirable to develop a fruit or vegetable salad preservative which does not contain sulfites, yet which can be used effectively to prolong shelf life particularly for salad bar ingredients and pre-prepared salads. It is also desirable to develop a salad preservative which does not add any objectionable slimy, gummy or heavy mouthfeel to the salad ingredients.